The present invention relates to a storage system and a control method thereof.
In a database system handling vast scales of data such as a data center, data is managed using a storage system configured separately from a host system. For example, a disc array system is well-known as this kind of storage system. In a disc array system, a large number of disc drives arranged in an array are managed as a RAID (Redundant Array of Independent Inexpensive Disks). At least one physical unit is then formed on the physical storage region provided by the large number of disc drives and this logical unit is provided to the host system. The host system then recognizes the logical unit as a single physical device and accesses data on the logical unit.
This type of storage system is taken as a measure for reliably preserving data should accidents etc. occur. For example, a system with a high fault tolerance is disclosed in Japanese Patent Laid-open Publication No. 2005-293469 where data written to a primary storage control device is remote copied to a secondary storage control device so that the data is duplicated.